Work in C. elegans has defined a signaling pathway that controls longevity and response to stress. Loss of function alleles of the insulin-growth factor receptor (Daf-2) or PI3'K (age-1) lead to 2-3x longer life and powerful resistance to stressors such as UV irradiation, oxidative insult and heat. All of these beneficial actions are mediated by the transcription factor, Daf-16. While Daf-16 is widely expressed, the pro-longevity effects are mediated by Daf-16 activity in specific tissues. This indicates that Daf-16 participate in a conversation among tissues that ensures coordinated responses to environmental changes and metabolic function. Mammals have four Daf-16 orthologs and FOXO3 is the phylogenetically the closest - based on sequence and function. Promotion of nuclear localization of FOXO3 is strongly neuroprotective in multiple models of neurodegeneration. Understanding the role of FOXO3 in vivo will require spatio-temporal control of its nuclear localization. In this tool-development proposal we will make transgenic mice in which FOXO3 is fused to the ligand binding domain of the estrogen receptor (a tamoxifen-sensitive version called ERT). When inserted into the CAGGS-floxed-STOP vector we will be able to express FOXO3 in a cell-type specific manner and drive it nuclear by administration of tamoxifen. In this proposal we will characterize these mice for transgene leakiness, tissue specific expression, off target effects and tamoxifen inducibility of FOXO3 target gene expression. The deliverable of this proposal is a versatile mouse that permits spatio-temporal control of FOXO3 gene transcription.